Control of a jet expelled from an annular orifice



Sept. 12, 1967 3,340,944

CONTROL OF A JET EXPELLED FROM AN ANNULAR 01111 1013 D. F. WHITE ETAL Filed May 10, 1965 Fig. I.-

Prior Art Controluble Suction Source ATTORNEY United States Patent 3,340,944 CONTROL OF A JET EXPELLED FROM AN ANNULAR ORIFICE Douglas F. White, Bedminster, and Gunnar Heskestad, East Brunswick, N.J., assignors to American Radiator & Standard Sanitary Corporation, New York, N.Y., a

corporation of Delaware Filed May 10, 1965, Ser. No. 454,496 9 Claims. (Cl. 180-7) This invention pertains to the directional control of a jet expelled from an annular orifice and, more particularly, to the inward deflecting of a peripheral jet of a ground effect machine.

Fluid, under pressure, which is expelled from an annular orifice can be used to do work. One specific use is with ground effect machines, generally designated as GEMs. Such machines are airborne vehicles which are also called flying platforms or hoverplanes. In such a vehicle, air above the vehicle is scooped into the vehicle and expelled, under pressure, from the bottom of the vehicle toward the ground, or similar surface. The reaction of the surface to the pressurized fluid causes the vehicle to ride over the surface on a cushion of fluid.

The operating height of the vehicle is a function of the rate of fluid flow. The pressure of the air beneath the GEM must be higher than the surrounding atmospheric air. This region of higher pressure must be contained by some means. One way of creating the high pressure region is to surround it by a properly directly high velocity curtain of air around the periphery of the GEM. In peripheral-jet type ground effect machines it is desirable to add a radially inward component of velocity to the expelled fluid to increase base pressure.

Presently available ground effect machines of the peripheral jet type are now provided with contoured orifices to obtain the inwardly directed flow, and are also provided with flexible skirts which extend from the outer edge of the orifice to increase the operating height.

In addition, with such machines, changes in operating height are obtained by varying the rate of flow of fluid from the orifice. Since the flow is derived from a mechanically driven impeller, it is necessary to provide complex controls for varying the speed of operation of the impeller.

Furthermore, such machines are subject to tilt. Therefore, some .means must be included to restore the machine to its stable orientation. Heretofore, complex secondary controls were employed.

It is, accordingly, a general object of the invention to provide an improved method for radially inwardly directing a high-speed jet of fluid expelled from an annular orifice or outlet.

It is another object of the invention to provide an improved method of directing a jet expelled from a peripheral-jet type ground effect machine.

It is a further objectof the invention to provide an improved method of controlling the operating height of a peripheral-jet type ground effect machine.

It is yet another object of the invention to provide an improved method of enhancing the stability of ground effect machines.

It is a still further object of the invention to satisfy the above objects with apparatus that is simple, reliable and inexpensive. a ,7 r

Briefly, the invention contemplates raising the base 3,340,944 Patented Sept. 12, 1967 ice pressure of a jet fluid that is being expelled from an annular outlet. The annular outlet has inner and outer peripheral edges. Suction is applied to the fluid along the inner effect machine, and for controlling the rate of suction to vary the operating height of the machine, and for controlling the regions of application of suction to enhance the stability of the machine.

Other objects, features and advantages of the invention will be apparent from the following detailed description, when read with the accompanying drawing, which shows, by way of example and not limitation, apparatus utilizing the invention.

In the drawing:

FIG. 1 shows a vertical sectional View, partially in schematic, of a peripheral-jet type ground effect 'machine; I

FIG. 2 shows a vertical sectional view, partially in schematic, of a peripheral-jet type ground effect machine practicing the invention; and

FIG. 3 shows the details of one of the peripheral edges.

Referring now to FIG. 1, there is shown a prior art ground effect machine 10 of the peripheral-jet type hovering over the ground G. Machine 10 which is axially symmetrical about center line C includes an outer housing 12 and an inner housing 14. The housings are spaced from each other to provide an annular conduit 16 for fluid such as air. Conduit 16 has an inlet 18 and an annular outlet 20. The portions of the housings 12 and 14 in the region of the outlet 20 are so contoured that fluid represented by streamlines 22 is directed downward toward the ground G and radially inward toward center line C.

Within inner housing 14 is a rotary source of power. such as engine or motor 24. A shaft 26 connects motor 24 to impeller or fan 28 located in the inlet 18.

Fan 28 scoops air represented by streamlines 30 into inlet 18 and drives it under pressure through conduit 16 to the outlet 20 thereof. The air is expelled from annular outlet 20 in the form of a peripheral jet. When the rate of flow of the fluid is sufficiently great the machine 10 rises from the ground G.

In order to increase the operating height a skirt 32 of flexible material extends downwardly from the outlet peripheral edge 34 of outer housing 12.

Although, a machine such as the machine 10 can operate, it has several limitations. Its stability with respect to tilt is limited and means for applying positive restoring forces must be provided. Furthermore, operating height control is solely dependent on the rate of fluid flow. Therefore, elaborate systems to control the fan speed must be provided. In addition, much of the pressure is expended in the turbulences created by the contouring of the conduit defined by the housings.

These problems are eliminated in the ground effect machine of FIG. 2. Machine 50 includes an outer housing 52 and an inner housing 54. The walls of the housings define an annular conduit 56 with the outside wall 58 of housing 54 being the inner wall of the conduit and the inside wall 60 of housing 52 being the outer wall of the conduit. Annular conduit 56 has an inlet 62. A

Q) rotary impeller or fan 66 located at inlet 62 is connected via shaft 68 to a motor 70, within housing 54.

Conduit 56 has an annular outlet 64. The inner peripheral edge of the annular outlet 64, i.e., the peripheral edge of wall 58, in the region of the outlet 64, is provided with a peripheral slot 72. Peripheral slot 72 is connected to controllable source of suction 74A and 74B.

Assume for the time being that no suction is applied to slot 72. Then, as fan 66 rotates, air represented by streamlines 76 is scooped into the conduit 56 and expelled generally downward from annular outlet 64. However, it has been found that by applying suction to the fluid flow past the edge of a conduit discontinuity, the fluid can be diverted around the discontinuity. The peripheral edge of wall 58, in the region of the annular outlet 64, is such a discontinuity. Therefore, when suction is applied to peripheral slot 72, the fluid represented by streamlines 78 is deflected radially inward toward center line C.

The degree of deflection is a function of the rate of suction for a given gap geometry. The gap width W (FIG. 3) should preferably be greater than one onehundredth of the jet width and the angle A of the plane of the gap width surface 58 should be between the range of 30 to 90. Furthermore, the degree of deflection controls the base pressure exerted by the expelled fluid. Therefore, by controlling the rate of suction, the operating height of machine 50 is controlled.

Additionally, it is believed that if machine 50 tilts with respect to the ground G, an automatic restoring force is created, by virtue of the edge suction effect, to return the machine to the horizontal. However, if a more positive restoring force is required suction can be applied selectively to portions of the peripheral slot. For example, slot 72 can be divided into peripherally extending regions each connected to a separate controllable source of suction such as sources 74A and 74B. Or else, either portions of the slot 72 can be controllably blocked or the gap width of portions of the slot can be changed.

If desired, it is also possible to include a skirt 80 of flexible material extending from the peripheral edge 82 of wall 60 to increase the operating height.

Furthermore, with a ground effect machine it is desirable to provide edge suction in the discontinuity region of conduit 56 where the direction of fluid flow changes from the horizontal to the vertical direction. Therefore, there is provided the peripheral slot 84 which is connected to a source of suction 75A and 75B. Hence, the fluid is guided around a right-angle bend with a minimum of turbulence.

There has thus been shown improved methods and apparatus for radially inwardly directing a fluid expelled from an annular outlet. The use of suction applied to the inner peripheral edge of an annular outlet, simply and efliciently provides the inward deflection which may be profitably utilized for peripheral jet GEMs. More specifically, there has been shown methods of utilizing peripheral edge suction to improve the efliciency, simplify the control and enhance the stability of ground effect machines.

While only one embodiment of the invention has been shown and described in detail, there will now be obvious to those skilled in the art many modifications and variations satisfying many or all of the objects of the invention but which do not depart from the spirit thereof as defined in the appended claims.

What is claimed is:

1. In a ground effect machine, the combination comprising: an outer housing including a top portion and a downwardly extending side portion, said top portion being provided with a central opening; an inner housing disposed within said outer housing, said inner housing including a top portion parallel to and spaced from the top portion of said outer housing, and a side portion parallel to and spaced from the side portion ofsaid outer housing, the peripheral edge of said inner housing where the top and side portions thereof meet being provided with a peripheral slot of predetermined length; means for drawing fluid into the central opening and impelling the fluid, under pressure, through the region between said housings to the region below said housings; and means for applying suction to portions of said peripheral slot.

2. In a ground effect machine comprising two fixed housings one embraced within the other so that the bottoms of both housings are substantially coplanar and the space between both housings providing a conduit through which a jet of fluid is directed toward the ground, the peripheral edge where the bottom and a side wall of the inner housing meet being provided with a peripheral slot positioned at a predetermined angle with respect to the side wall, the method of directing the jet of fluid radially inward, which consists in applying suction to the peripheral slot.

3. The method of directing a jet of fluid as defined by claim 2, in which the rate of suction is controllable.

4. In a ground eflect machine comprising an outer rigid housing having an open bottom and an inner rigid housing having a bottom and side walls which are spaced from the outer housing so that the respective housings provide outer and inner peripheral edges through which a jet of fluid is directed toward the ground, the bottom of said inner housing and the lower extremity of the outer housing being substantially coplanar, the bottom and the side walls of the inner housing being provided with a peripheral slot positioned at a predetermined angle with respect to the side walls, the method of directing the jet of fluid radially inward, which consists in uniformly applying suction to the peripheral slot.

5. In a ground effect machine comprising two fixed housings one embraced within the other so that the bottoms of both housings are substantially coplanar and the space between both housings providing a conduit through which a jet of fluid is directed toward the ground, the peripheral edge where the bottom and a side wall of the inner housing meet being provided with a peripheral slot positioned at a predetermined angle with respect to the side wall, the method of changing the angle of tilt of the machine with respect to the ground, which consists in discontinuously applying suction to portions of the peripheral slot.

6. In a ground effect machine comprising two fixed housings one embraced within the other so that the bottoms of both housings are substantially coplanar and the space between bothhousings providing a conduit through which a jet of fluid is directed toward the ground, the peripheral edge where the bottom and a side wall of the inner housing meet being provided with a peripheral slot positioned at a predetermined angle with respect to the side wall, the method of changing the angle of tilt of the machine with respect to the ground, which consists in applying suction to the fluid along selected portions of the peripheral slot.

7. In a ground effect machine comprising two fixed housings one embraced within the other so that the bottoms of both housings are substantially coplanar and the space between both housings providing a conduit through which a jet of fluid is directed toward the ground, the peripheral edge where the bottom and a side wall of the inner housing meet being provided with a peripheral slot positioned at a predetermined angle with respect to the side wall, the method of changing the base pressure of the jet of fluid being expelled through the conduit which consists in applying suction to the peripheral slot so that the path of the jet of fluid is changed.

8. In a ground efi'ect machine, the combination comprising: a fixed housing including inner and outer Walls each provided with a bottom, the bottoms of which are substantially coplanar, an inlet and an outlet in said housing, means for impelling fluid for expulsion, under pressure, from said inlet through said outlet, the edge portion of said inner wall adjacent the bottom being 5 6 provided with a peripheral slot of a width greater than References Cited one one-hundredth of the spacing between the inner and UNITED STATES PATENTS outer walls and positioned at a predetermined angle with 3 203 49 19 5 Cockereu 1 0 7 respect to said inner wall, and means for applying suc- 5 3,215,218 11/1965 Hurst 180-7 tion to said peripheral slot, 3/1966 Hart et 3,244,244 4/1966 Cockerell 180-7 9. A ground eflect machine according to claim 8, in which the suction applying means includes means for applying the suction at a controllably variable rate, A. HARRY LEVY, Primary Examiner.

3,265,141 8/1966 Cossairt et al. 1807 

2. IN A GROUND EFFECT MACHINE COMPRISING TWO FIXED HOUSINGS ONE EMBRACED WITHIN THE OTHER SO THAT THE BOTTOMS OF BOTH HOUSINGS ARE SUBSTANTIALLY COPLANAR AND THE SPACE BETWEEN BOTH HOUSINGS PROVIDING A CONDUIT THROUGH WHICH A JET OF FLUID IS DIRECTED TOWARD THE GROUND, THE PERIPHERAL EDGE WHERE THE BOTTOM AND A SIDE WALL OF THE INNER HOUSING MEET BEING PROVIDED WITH A PERIPHERAL SLOT POSITIONED AT A PREDETERMINED ANGLE WITH RESPECT TO THE SIDE WALL, THE METHOD OF DIRECTING THE JET OF FLUID RADIALLY INWARD, WHICH CONSISTS IN APPLYING SUCTION TO THE PERIPHERAL SLOT. 